A variety of valve actuating devices, primarily for internal combustion engines, have been heretofore suggested and/or utilized which include arrangements for variation of valve timing, of valve duration, and/or valve lift (see for example Nov. 20, 1989 Automotive News, "Computer Valve Train May Hike Power, MPG", "A Review Of Variable Valve Engine Timing" by C. Gray, in the SAE Technical Paper Series, No. 880386, "The Synthesis And Analysis Of Variable-Valve-Timing Mechanisms For Internal-Combustion Engines", by F. Freudenstein, in the SAE Technical Paper Series, No. 880387, and "A Survey Of Variable Valve Actuation", Automotive Engineering, January 1990). Such heretofore known devices have included hydraulic valve lifters (see U.S. Pat. Nos. 4,122,884 and 4,231,543), pneumatic valve lifters (see, for example, "Computer Valve Train May Hike Power, MPG", Automotive News, Nov. 20, 1989) and various mechanical approaches to valve event variability (see for example U.S. Pat. Nos. 4,577,598, 4,387,674, 4,388,897, 4,061,115, and "Continuous Cam Lobe Phasing", Society of Automotive Engineers, 1987).
The use of variable valve actuating devices has been recognized to provide numerous advantages including, for example, fuel economy advantages (see "Effect of Variable Engine Valve Timing On Fuel Economy", by T. H. Ma, SAE Technical Papers Series, No. 880390), and the opportunity for controlling engine load without a throttle plate (see "Variable Valve Timing--A Possibility To Control Engine Load Without Throttle", by Lenz, Wichart, and Gruden, SAE Technical Paper Series, No. 880388).
However, those devices which have been heretofore suggested and/or utilized have not always provided devices which are durable, which are conservative of engine power (see "Computer Valve Train May Hike Power, MPG" Automotive News, Nov. 20, 1989), are adaptable to either existing spring-loaded poppet valve systems or desmodromic systems, have the desired response to command time and cycle-to-cycle and cylinder-to-cylinder repeatability, lend themselves easily to computer control without continuous or high power supply requirements, and/or which are adjustable over a wide range in the normal operating cycle of the engine for controlling valve opening and, independently, valve closing at any selected time in an engine's operating cycle.